The problem with just about every virtual desktop implementation is just that - they're virtual. This means that beyond the ability to move windows to specific desktops, you're still looking at exactly the same desktop, no matter what virtual desktop number you switched to. A mockup for GNOME Shell is trying to take the virtual out of virtual desktop.

This is what activities are supposed to be in KDE (basically this is the vision we laid out 3 years ago) and Nepomuk is being adapted to provide ontologies for it.

Yeah. I thought we were progressing towards content semantic desktops and not, like this proposal, sticking file based desktops. It makes no sense to me having multiple Desktop folders: I use no Desktop folder or use it as a download, rubbish bin folder. I think most people does the same and that it make sense no more: semantic desktops are the way to go, IMHO.